Time delay controlled remote station transmission to central data collecting station



April 5, 1966 Filed June 28, 1961 W. M. WITTENBERG TO CENTRAL DATA COLLECTING STATION 17 Sheets-Sheet 1 T1 T2 T3 T4 T5 T6 T7 T8 T9 0M IM 0M 1M 0M "1M I 'T F' l ICR RT} ICRvMTI K {0R L J 1 :IE/JTB l J1 12 A 109 GARY/m D84 T T [As-22 T F 11 05-52 T PM D M D D M D D M DPC 102 0s-4- M FIG.2 OUTPUT MULCOM LOGIC TS TIMING PULSE CHECK BIT m6 TERMINAL ADDRESS 10 LINES T0 SETH \209 DATA 7 LINES SETS TERM ADDR i PARITY ALARM 21s 21s ENCODER 3 220 RESET PARITY A LRG GENERATOR RESET REGTSTER m 204\ SYNC RESET TA CHECK LRH TIMING 215 RING 11 CHARACTER A-MA ECEIVED g RECOGNITION 2o? MULGOM 405 mum; k

PULSES T 205 TRuT sRIR T 206 CONTROL DATA REGISTER(OSR)/ INVENTOR o- T TQ WILL/FORDMWITTENBERG SUBSET BY @141 T DEMODULATOR 212 j ATTORNEY W. M. WITTENBERG April 5, 1966 TIME DELAY CONTROLLED REMOTE STATION TRANSMISSION TO CENTRAL DATA COLLECTING STATION 17 Sheets-Sheet 2 Filed June 28, 1961 wmm m 0222C. EOQJDE FDQPDO m2 5 :5 32: 3:2: :20 a: kmm K IV E; w w $2222: :2 EESEMF 2:; 225 .26 3 :0: N 5 5:: 5: a; 2:525 0 :5 E F L E: f E; i L .2: 3 II E E: 2 mwE JL 4 L T 713 P 2 Tlllll. :0: a; L L L 5 H April 5, 1966 w. M. WITTENBERG TIME DELAY CONTROLLED REMOTE STATION TRANSMISSION TO CENTRAL DATA COLLECTING STATION 17 Sheets-Sheet 3 Filed June 28, 1961 dllllw j E:

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April 5, 1966 w. M. WITTENBERG TIME DELAY CONTROLLED REMOTE STATION TRANSMISSION TO CENTRAL DATA COLLECTING STATION 17 Sheets-Sheet 4 Filed June 28, 1961 E; 7 E25 53% am 0 E .T 2 52 v2 CE: 5 w is: 2 ms :2 if 1 5% J22 2:2: N 1 ET 1 F Lfim 2a 2: 2% 3 \QE 1 33:28 v $2550 55;: 52;: 02; 2: Em 2% 3L mam am 2 m m a? 2:52: 8 :2; oz: E52 :52 aw 2 325% 2 L33: A 33$: W L L Z Li. 5522 ll. E 21 M E :223? E o :23 N E5 5% 1 52a m\ l m l 202 L 2w 5Q 52:55 :2 720w mo; e 22:53: i aw ET 6 223 E; 525: E E 52% am E 1 s; 3 2% 25:23 go 5L 2% Q: i 552:2? T 23;: E 2 1|:1l mm :52 0 2% M 23m $22: z zfi 55 :25 m- E: w 8

3w 050 EOQJDE P3n z April 5, 1966 w. M. WITTENBERG 3,244,804

TIME DELAY CONTROLLED REMOTE STATION TRANSMISSION TO CENTRAL DATA COLLECTING STATION Filed June 28, 1961 17 Sheets-Sheet 5 I l a. S L l .L

U) L T I (D f .J .L. D D.

"T L) S z l Q iw a 0- E L...- u. 0 O

J D 2% E L D -1 1 2 Z L T 3; g x z 5 5 g 5: E g 2 2 z v Q Q w a z c r- O: ro i 4 N Si N q LO (Q g N H .4 I- l-- T 1 SPECIAL l 1966 w. M. WITTENBERG 3,

TIME DELAY CONTROLLED REMOTE STATION TRANSMISSION TO CENTRAL DATA COLLECTING STATION Filed June 28, 1961 17 Sheets-Sheet 6 DEHODULATOR 5 INPUT 808 MODULATOR 807 so AHEAD RECOGNITION (GAR) H31 m 0 4 1 1 1 1; A RE 0 1001 1010 NEW s1110 2 1001 J 5 I SS u 10 1 i sPE01111 1,010 L: 1 E "TO +A SS B 1009 m i I T4 1012 r 1021 11 A REC 101 1025 1022 1 +15 5111111 ss T TV -0 1019 1 1005 l I I 1 I 1005 111111151111 1 1 I i f 1 I 0 11 RESET ss TV I -TO 1020 1025 10211 i I 311111 RESET I 1 1 l 1 l -s CARR me 011 A i TO EL M Q 1 1 1 W. M. WITTENBERG 3,244,804 TIME DELAY CONTROLLED REMOTE STATION TRANSMISSION TO CENTRAL DATA COLLECTING STATION 17 Sheets-Sheet '7 Filed June 28, 1961 Cami: Q! N L| EEE 2o: 2 N LEPPEEH sow :2 P

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M 5, W W. M. WITTENBFEIWG fifimflfl CONTROLLED R TIME DELAY EMO S TION TRANSMISSION TO CENTRAL DATA COL T G- STATION Filed June 28, 1961 17 Sheets-Sheet 8 2 INPUT LOGIC 3 ENPUT LUGIC BLDCK BLOCK 1405 B 100WFd J HOLD Li April 5, 1966 w. M. WITTENBERG 3,244,804

TIME DELAY CONTROLLED REMOTE STATION TRANSMISSION T0 CENTRAL DATA COLLECTING STATION Filed June 28, 1961 17 Sheets-Sheet 1o H6 17 OUTPUT TIMING +30 TTOT +3 SYNC RESET +5 2K0 CK 0P *8 SYNC RESET +8 H08 AD ANCE 2 KC CK (TP OUTPUT DELAY +8 T6B SPECIAL +8 I 2K0 CK 0P +5 T65 SPECIAL April 5, 1966 w. M. WITTENBERG 3,244,304

TIME DELAY CONTROLLED REMOTE STATION TRANSMISSION TO CENTRAL DATA COLLECTING STATION Filed June 28, 1961 17 Sheets-Sheet 11 G EOM RECOGNITION EOM +s EOM +SOSRB1T841 LRC 1110311 1012 1 To -+A TO +8 CHECK LRC +5101 SPECIAL S 5 fg s s s s s +3 15 1 1 F 1 1 s EOM 1 I i 1 1 I I 1 1 1 1 To +A i i S S S S I 1 l I -s TGR RESET -TO IP DE s RESET 1011 s s' s s s +5 14 GAORMA +5 011 OR 11111011 1 +A "TO 1804 S 5 PS -1809 i i 1811 I 1 +SGAORMA +s1101c11 1 --To I 5 F 8 s ,s s s' 11112 +s110111 11111 +5 15 I F W9 #1808 :l +A +A I s ,s\ F3 3 s s +s 1101 11110 SYNC /-1B07 +s 3111c -s 3110 RESET =-TO 1803 f 1 1 1 1 +A TO 5 S L S April 5, 1966 Filed June 28, 1961 W. M. WITTENBERG TIME DELAY CONTROLLED REMOTE STATION TRANSMISSION TO CENTRAL DATA COLLECTING STATION 17 Sheets-Sheet 13 :5 TO INPUT CONTROL MONITOR" +s REQTO TRANSMTT/ 5500 +5 551m 2001 TRANSMIT '2008 2010 RESET 2004/ +5150 CK +A TO w M -5 OFF UNE TV 5 s s s 4015 MI I 9 T +s NOT MON MODE 2005 l T 200 T 5 -s XMTT 2029 l l 2012 l 2050 AG TGR RESET TV --+A Y-TO L I DE *SSYNCZ +SSTARTSCAN F8 S --S S S S S S +500 LINE \F I +5 REQ TO 5500 M To 5ND 2022 +5 RESET -s 00 1 -s GATE BA 04 -s CLEAR T0 0 I O 2025 SEND s s 2021 s s s s 2005 s SYNC 1 3 T4 i i 201T\ 2024 +8 GATE BA 84 l g 50001 ,2010 50102 L -+5 CTR To SEND -S GATE EON S S S S ""S S 'S S S S I 2007 F! l 5 T6 5 i 2019 ZEOZB 2054 SPECIAL 2015 I T +8 NOT SYNC 2\ -1 i L i T -s SYNC 2 T +A "To- L +A '1 TO DE {T028 8 )8 F8 8 S S -S S 20 S S- 2015 +5 SYNC 1 5ND GA PM 2055 +SSEND 0A +s 2000555000 TV +5 NOT L50 3 2041 2036 2059 +A L +A TV'F'ZOZ'S s s s s *STGR F -s GATE GA RESET 2044 2040 +ST5IP 2045 DELAY 2048 2045 2055 2041 +A -T0 +A S S S S 2050 S s 2052 Li i +A -To +511 SPECIAL S S I s S\2049 2051 April 5, 1966 M. WITTENBERG TIME DELAY CONTROLL TO CENTRAL DATA COLLECTING STATION Filed June 28, 1961 ED REMOTE STATION TRANSMISSION l7 Sheets-Sheet 14 TATPUT AAEss-AGE ASSEMBLY FIG, 21!

s LRC DTTD 21o4 -5 MA DTT B -0' -s Ts SITE ,5 5 -11 DATA BH 0 T I -s LRC BIT A -s MA BIT A t 1 21111 +s INPUT BITC 22110O53\ E +A T LO C S S S S S S R R 8 +3 GATEBA84 \2115 R DATA BITB 2H6 -s TS BIT A 1 1 -s GATE BA 84 #2102 L 1 L L +s INPUTBITB -s LRC ans 0 E 2101 T S S R flu-R s 2108 -R DATA W A -s Ts BIT a 1 1 L L +s INPUT BIT A E s s R R s 2119 R DATA BIT8 4106 H2109 2107 8 WE GA T L L +s INPUT BIT8 *3 LRC BIT 4 S S R R S 1 1 R DATA 8H4 -s LRC BIT 2 /2H0 s MA em I 2122 s MA DTTA 1 i LL 4 5 TS EH4 E +s111PuT BIT -11 DATA BIT 2 (/2123 -s Ts BIT2 T 1 MM BIN Q5 2 L A +s INPUT D|T2 -s GATE EOM s s s s R R 5 1 I I i 1 i R DATA DTT 1 1 -s SYNC 2 i i I -SLRC D1T1 1E1 A +s111P11TD1T1 2111 -11 RD DATA April 5, 1966 w. M. WITTENBERG 3,244,804

TIME DELAY CONTROLLED REMOTE STATION TRANSMISSION TO CENTRAL DATA COLLECTING STATION Filed June 28, 1961 17 Sheets-Sheet 16 +12 F|G.23 F|G.25 POWER INVERTER (1P) DRIVER, 2.2K EMITTER B FOLLOWER FIG. 24

2509 REMOTE LOAD (R) I FIG. 27

POWE R DRIVER (DP) FIG.28

April 5, 1966 w. M. WITTENBERG TIMEDELAY CONTROLLED REMOTE STATION TRANSMISSION TO CENTRAL DATA COLLECTING STATION Filed June 28, 1961 17 Sheets-Sheet 1'2 :5 m5 MU H .HH EH T: F a H H f M EP "FE refi Er @P WP @P DP United States Patent i 3,244,804 TIME DELAY CONTROLLED REMOTE STATION TRANSMiSSION TO CENTRAL DATA COLLECT- ING STATION Wilford M. Wittenberg, Poughkeepsie, N.Y., assignor to International Business Machines Corporation, New York, N.Y., a corporation of New York Filed June 28, 1961, Ser. No. 120,385 2 Claims. (Cl. 1783) This invention relates to communications systems, and more particularly to address techniques for communications systems.

Telegraphic, telephonic, and radio communications systems with remotely interconnected or controlled stations and exchanges have been used extensively for data communications, telemetering and person to person or station to station transfer of information. Specialized addressing equipment has been designed and has performed its functions satisfactorily within the intended environment.

In the past decade, there has been a tendency to broaden the usefulness of communication systems by developing real-time data processing systems in order to meet the ever increasing demands and complexities of modern business and scientific endeavors. Systems of this nature generally have a multitude of remote terminal stations which are interconnected with a centrally located data processing system or control center. In the real-time applications, problem factors or inquiries are entered at the remote stations, and transmitted to the data processing center for appropriate computation. Replies are generated by the data processing center and transmitted to the remote stations. A complete transaction, involving an inquiry and a reply, is usually completed in a fraction of a second.

The communication lines and equipment generally operate in millisecond time intervals, while the data processing system, being much faster, operates on the basis of microsecond intervals. Because of this differential in time, data processing system need not direct all of its activities to the intercommunication (real-time) activities. Since the data processing center is usually of a general purpose nature, it can be used for solving other matters not related to the real-time aspects of the system. These matters may include the preparation of reports of a general business or accounting nature, statistical reports, file maintenance and other non-real-time applications.

In this manner, the data processing center is capable of handling, in their entirety, a wide range of requirements for a particular business.

Because of the dual nature of .a system of this kind, it is desirable to free to data processing center from as many of the intercommunication control functions of the system as possible.

This invention is concerned with relieving the data processing center of a major portion of the addressing functionsnormally encountered in a communications not work.

In the prior art, the addressing functions of a particular system have been more or less concentrated at a control center or central exchange in order to maintain closer supervision and control of the system. Addressing of remote stations in order to notify them-to transmit messages has been primarily under control of the central station or exchange. In many instances, additional time has been required at the central station for receipt of an answer-back signal from any addressed station, for acknowledgement purposes. Prior art addressing techniques of this kind require that a considerable amount of the available operating time of the center be devoted to the addressing activities.

"ice

This invention is predicated on the concept that any central station time saved by a reduction in addressing activities can be used to advantage in other processing activities.

Accordingly, an object of the invention is to provide an addressing technique for a multi-station communication system which results in a considerable savings in time for the central station.

Another object of the invention is to provide a communications system addressing technique which is straightforward and free of the complexities of prior art addressing techniques.

A further object of the invention is to provide an addressing scheme which insures that each of a number of stations is given the opportunity to gain access to a common line without interference, one among the other.

Another object of the invention is to provide a communication network in which demands on the central stations time are minimized, but in which control of the network is retained in reserve by the central station.

It is another object of the invention to provide a communication addressing scheme which inherently and automatically continues to function, even though portions of the communications network may become inoperative.

Another object of the invention is to provide a communication addressing technique which is equally effective with a few remote stations as with a great many remote stations.

A still further object of the invention is to provide a communication system in which the direct and positive addressing techniques of the prior art are minimized and in which an indirect addressing technique is predominant.

Another object of the invention is to provide a time multiplexing addressing technique which may be effectively employed at any information transfer level within a communication system, and which has universal application.

Still another object of the invention is to provide a com munication network in which addressing is eifected by digital code permutation signals in conjunction with analog signals.

An additional object of the invention is to provide a system in which digital signals are used during certain portions of the addressing sequence, while analog signals are used during other portions of the addressing sequence, thus combining the advantages of both types of signals.

Another object of the invention is to provide .a system in which the addressing functions can be initiated entirely with analog signals. 3

In order to accomplish these and other objects, there has been provided in accordance with the present invention, a communication system which includes a central station interconnected with a plurality of remote stations, wherein addressing sequences for establishing line time for each remote station are initiated by the central station and are subsequently continued by said remote stations without control or intervention of the central station, under normal circumstances. In accordance with the invention, a go-ahead signal sent by the central processing unit and accompanied by an appropriate address is recognized as a signal to commence transmitting by the unit to which the address relates. At the end of transmission, a go-ahead signal is sent out by the addressed unit; the go-ahead signal starts a timeout in each subsequent unit, and the unit having the lowest time-out following the receipt of the go-ahead message will commence transmitting; units with longer time-outs are prevented from transmitting by the presence of a transmitted carrier from the unit having the lowest time-out.

A related, but distinct invention of the same-assignee is found in US. patent application Serial No. 120,771,

ments of the invention, as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 represents a communication system in which the invention is incorpora ed.

FIG. 2 is a more detailed representation of the output portion of a multiplexing unit depicted in FIG. 1.

FIG. 3 represents pulses normally encountered in the output multiplexing equipment of FIG. 2.

FIG. 4 represents interconnections between certain of the equipments of FIG. 1.

FIG. 5 represents a typical sequence of operations in the device of FIG. 2.

FIG. 6 is a more detailed representation of an input portion of multiplexing equipment shown in FIG. 1, the representation being illustrative merely, and not corresponding on a block-by-block basis with those of its component circuits which are shown in other figures herein.

FIG. 7 represents pulses normally encountered in the equipment of FIG. 6.

FIG. 8 represents interconnections among certain other equipment in FIG. 1.

FIG. 9 is a graphical representation of a typical sequence of operations in the input multiplexing equipment of FIG. 6.

FIG. 10 is an address recognition circuit which has particular usefulness in the practice of the invention including several segments of the equipment shown in FIG. 6.

FIGS. 11-15 are basic circuit blocks which are used in the invention.

FIG. 16 is a synchronization recognition circuit provided in the output multiplexing equipment of FIG. 2.

FIG. 17 is a timing circuit in the equipment of FIG. 2.

FIG. 18 is a character recognition circuit in the equipment of FIG. 2.

FIG. 19 is a control circuit in the equipment of FIG. 2.

FIG. 20 is a control circuit in the input multiplexing equipment of FIG. 6.

FIG. 21 is a message assembly circuit in the equipment of FIG. 6.

FIG. 22 is a message format circuit in the equipment of FIG. 6.

FIGS. 23-28 are additional basic circuit blocks which are used in the invention.

FIG. 29 is an alternative embodiment of the inventiou, merely illustrating that the invention herein may be utilized in the terminals as well as in the multiplexing communication control units.

The following description covers a communication system, within which the present invention may be utilized.

The heart of the invention, as illustrated primarily in FIG. 10 (description begins in the section entitled Go Ahead Message Mulcom to Mulcom), relates to the ability of the various remote units to control scanning of themselves so as to permit them to initiate message transmission in an orderly polling or calling sequence. This is achieved by means of go-ahead signals which each unit can transmit at the end of its message transmission. Each unit monitors the transmission line and sets a trigger when a go-ahead is sensed. After a delay in time, which is determined by a single-shot circuit, each unit will test the line to see if any other unit has begun transmission: if no carrier signal is present on the line, the unit will generate a start signal which will permit that same unit to transmit. The time delay in each unit differs from that of any other unit so that the unit which is first in the sequence has a short time, and the unit which is later in the sequence has a correspondingly greater time. Thus, the unit with a shorter time will begin transmitting before the time-out of the delay for any unit subsequent in the sequence; this transmission will block all subsequent units from entering the transmit mode. The invention includes the ability to transmit as a result of the above-described polling, or in response to an addressed go-ahead sent to a unit by a central station as shown in FIG. 19 (S START). No low-ordered unit (2, 3) can be called into action by a go-ahead from a higher unit (5, 6) because the transmission lines 101, 102 are unidirectional; the signals are propagated along the lines through amplifiers; thus, the input line 101 transfers the signals from M1 to M2to M3- to DPC, and not vice versa.

The specification includes a description of closely related portions of a communication unit, including input and output portions, capable of practicing the present invention; the system is broadly described, and then the output portion of a unit, including addressed go-ahead message recognition, is described in detail; following that, the self-polled input unit is given detailed treatment.

In the drawings, the exact name given to each signal line is consistent and unique throughout the drawings; however, in order to assist in locating items in the drawings, the high-order digits of reference numerals comprise the figure number of the figure where the item is shown in context with the description.

The following charts indicate the relationship of hardware shown in more than one figure.

FIG. 1

OM=FIG. 2 101:613 CR=219 102=212 109, 111=FIG. 10; 611 112, 113=(g0es from 611 MT=625, 626, 627, 628, to 626); 1027 FIG. 2 204=FIG. 17 214 404 219=FIG. 16, FIG. 18, 220:4.07

FIG.19 217:1803; 1640*, 1641 215=-v02 212:102 202:401, 403 207=S START (FIG. 6), 211, 216:405 1004, 1931 209:406

FIG. 6 611 and 626=FIG. 1O 615=FIG. 21 625:2034, 2035 620 and 623=FIG. 22 644:2046, 2040, 2049 645:2252 612:2004 6117:2032 647:2033

FIG 10 INPUTS Line Name Ref No. Comes from Ref. 0. or

IG. No. Name 6 600. 6 Timing.

8 801. iii XMIT s GA Control Line From From DPO DPO. if desired.

1 Optional, to any unit.

FIG. OUTPUTS FIG. 19 INPUTS Line Name Ref. No. Goes to Ref. No. Line Name Ref. N 0. Comes from Ref. No. FIG. No. FIG. No. or Name New SYNC 8 803 +8 OSR Bits 2 206. +S Start 1005 2001 +8 T613 Special 1909 17 +S TGB Special +S Transmit 20 2008Eg+S R Qto FIG. 16 INPUTS Transmit] 10 s M Send). Line Name Ref. No. Comes from Ref. No. or A Blts 2 Name +s GA OR MA 1906 18 1813. +S Not GA OR MA 18 1811. OSR Bits 2 206. is i- 2K0 0K 0P 1607 17 +g g 1, +s ON Line (Operator switch) -s 'IGR Reset 2 204. a -S I 2K0 CK OP 4 401. I 19 OUTPUTS Line N eme Ref. No. Goes to Ref. No. FIG. 16 OUTPUTS FIG- No' o Name 20 Line Name Ref. No. G'ose to Ref. No.

+S GA 1913 -S Stnrt 1931 10 '1 0 1 404 +3 SYNC Reset 1641 17 1707 11 1mm S Reset LRC. 2 210. S S1 Nu Reset 1640 17,18 1708,1803 +8 TS Select"- 2 208.

,. +5 MAO" +8 Reed". FIG. 17 INPUTS +S N017 MAO- 18 +8 Not MAO.

Line Name Ref. No. Comes from Ref. No.

N0. FIG. 20 INPUTS SYNC Reset 1707 16 1641 Line Name Ref No Comes from Ref No or S 2KC OK OP- 4 401 s SYNC Reset. 1708 16 1640 Name +S Advance 2 204 I 2K0 CK 4 401 +s Start 2001 10 1005.

+s 1 KC CK 4 403. Kg%B(}l%L1i1ne%ta1t 6 1 k G ese 6 C 00 on- 17 OUTPUTS +5 ON Line 6 trol, I g 81 152 "266" 6 Line Name Ref. N 0. Goes to Ref. No. to 5 8 +S T4 17 +S T4. or Name -s Gate EOM- e 620.

n can. 6,8 6 ,6 9; 813. +8 OT 4 17 11 401 +s Not LRC 2039 22 +5 1 3 fi' -s TGR Reset a Special. 3 Timing. 16 1607. b 22 6 19 1909. 19 10 +8 T 22 S T S TGB pwal 7 gg Line Name Ref. No Goes to Ref. No. Te SPEC 10, 22, 20

+s REQ to Transmit/Send. 2004 s 807 FIG. 18 INPUTS +S MON Mode. 0 601 +5 Not MON Mode- 6 601 -S XMIT v 6 629 Line N eme Ref. No. Comes from Ref. No. +S SYNC 2. 2029 6 615 FIG. No. or Name +S Start Se2m 2032 6 634 +S REQ to Send- 8 807 +8 Reset 6 604 +OSR Bits 2 205. -S Gate BA 84 2023 21 2102 +S TGA Special 17 TGA -S SYNC 1.". 21 2020 Special. +S Gate BA 84. 2025 21 2116 +8 T3, T4, T5 1804 17 +3 T3, T4, +3 Clear to SCT1(1 2014 8 808 T5. +S Not SYNC 2.- 2054 22 -S TGR Reset 2 4. -S SYNC 2. 2028 21 2028 +8 Not GA 19 +5 Not GA +S SYNC 1. 2018 21 +s Not MAO 19 +s Not 6 +8 Send GA 2036 e 628 MAO. S Gate GA 2040 21 -S SYNC Reset 16 1640.

FIG. 21 INPUTS FIG. 18 OUTPUTS Line Name Ref. No. Comes from Ref. No. Line Name Ref. No. Goes to Ref. N 0. FIG. N0.

FIG. N0.

-S LRO Bits 6 603 +8 EOM 2 208 'S MA Bits 2 219. +8 Check LRC--. 2 208 S TS Bits 6 002 -s EOM 2 208 R Date Blts 6,8 643,815 2 208 +5 Gate BA 84-" 20 2025. 2 208 S Gate BA 84." .20 2023 18 (only) -S Gate GA 20 2040 19 1900 -S Gate EOM 6 620 19 S SYNC 2- 20 2028 2 204 S SYNC 1 20 2020 

1. A TIME DIVISION MULTIPLEX COMMUNICATION SYSTEM OF THE TYPE HAVING A MESSAGE SIGNAL TRANSMISSION CARRIER MEANS COMMON TO ALL OF THE STATIONS THEREOF, COMPRISING: A CENTRAL STATION AND A PLURALITY OF REMOTE STATIONS, EACH OF SAID STATIONS INCLUDING TRANSMITTING AND RECEIVING FACILITIES, SAID STATIONS BEING ARRANGED IN AN ARBITRARY SEQUENCE FOR POLLING PURPOSES; A PLURALITY OF MESSAGE TRANSMISSION MEANS, ONE FOR EACH OF SAID REMOTE STATIONS, EACH SETTABLE TO A MONITOR CONDITION OR TO A TRANSMIT CONDITION, ALTERNATIVELY, EACH OPERATIVE WHEN SET TO SAID TRANSMIT CONDITION TO CAUSE THE TRANSMISSION OF MESSAGES FROM THE RESPECTIVELY CORRESPONDING ONE OF SAID STATIONS ON SAID CARRIER MEANS, EACH OF SAID MESSAGE TRANSMISSION MEANS INCLUDING MEANS TO TRANSMIT A GOAHEAD SIGNAL AT THE END OF SAID MESSAGE, EACH OF SAID MESSAGE TRANSMISSION MEANS OPERATIVE WHEN SET TO SAID MONITOR CONDITION TO PREVENT THE TRANSMISSION OF MESSAGES FROM THE RESPECTIVELY CORRESPONDING STATION; A PLURALITY OF GO-AHEAD RECOGNITION MEANS, ONE FOR EACH OF SAID REMOTE STATIONS, EACH INCLUDING A TIMING DEVICE RESPONSIVE TO SAID GO-AHEAD MESSAGES TO ISSUE A DELAYED GO-AHEAD SIGNAL AFTER A PREDETERMINED TIME INTERVAL FOLLOWING ITS INITIAL RESPONSE TO ONE OF SAID GO-AHEAD MESSAGES, SAID TIME INTERVAL IN ANY ONE TIMING DEVICE BEING DIFFERENT FROM THAT IN ANY OTHER TIMING DEVICE, SAID TIME INTERVAL BEARING A DIRECT CORRELATION WITH THE POSITION IN SAID POLLING SEQUENCE OF THE RESPECTIVELY CORRESPONDING STATION, A TIME INTERVAL OF ONE STATION BEING LOWER THAN THAT FOR A STATION SUBSEQUENT THERETO IN SAID SEQUENCE; AND A PLURALITY OF START MEANS, ONE FOR EACH OF SAID REMOTE STATIONS, EACH RESPONSIVE TO A DELAYED GOAHEAD SIGNAL FROM THE RELATED ONE OF SAID RECOGNITION MEANS AND TO THE ABSENCE OF A TRANSMISSION ON SAID CARRIER MEANS TO ISSUE A TRANSMISSION START SIGNAL, SAID TRANSMISSION START SIGNAL SETTING THE RESPECTIVELY CORRESPONDING MESSAGE TRANSMISSION MEANS INTO SAID TRANSMIT CONDITION. 